CALL: FIT_GAUSSIAN


reference

  The histogram is referenced via a global variable that has usually
  been returned by a call to BOOK_HISTOGRAM or GET_HISTOGRAM. This
  argument may also be an expression that results in a histogram.

  The argument is not modified on return.

x

  A 1-dimensional vector that contains the abscissa of the
  points on which the fit is to be performed.

  This vector should have the same size as y.

y

  A 1-dimensional vector that contains the function values
  of the points on which the fit is to be performed.

  This vector should have the same size as x.

err_y

  Either a scalar which is interpreted as a common error
  on all function values (y) or a 1-dimensional vector of
  the same length as x and y and which contains for each
  point the error in the function value.

integral

  The contents of the fitted Gaussian.

  There is no need to initialise this argument - the initial
  value for the fitting procedure is set to the sum of the
  histogram or Y array.

  This argument must be modifiable, i.e. it can not be a constant
  nor an expression.

mean

  The central value of the fitted Gaussian.

  There is no need to initialise this argument - the initial
  value for the fitting procedure is set to the mean of the
  histogram or arrays.

  This argument must be modifiable, i.e. it can not be a constant
  nor an expression.

sigma

  The standard deviation of the fitted Gaussian.

  There is no need to initialise this argument - the initial
  value for the fitting procedure is set to the RMS of the
  histogram or arrays.

  This argument must be modifiable, i.e. it can not be a constant
  nor an expression.

errors

  The errors returned are the square roots of the diagonal elements
  of the covariance matrix, multiplied by a correction factor equal
  to:

       sqrt(chi**2/(#points - #parameters))

  This correction factor is equal to 1 if the errors to the data
  points have been assigned correctly.

  Errors are only returned upon request. The corresponding
  arguments must be modifiable, that is, they can neither be
  constants nor expressions.

options

  The options string may contain the keywords listed in the table
  below. The keywords should be separated by blanks or commas.
  Additional text may be added - no error message will be issued
  if unrecognised keywords are used.

  ---------------------------------------------------------------------
  Option     Meaning                                 Defaults
  ---------------------------------------------------------------------
  EQUAL      Assume equal weight of all points       Not default
  NOPLOT     Don't plot the histogram and fit        Default
  NOPRINT    Don't print details during the fit      Default
  PLOT       Plot the histogram with fit             Not default
  POISSON    Assume Poisson errors                   Default
  PRINT      Print details during the fit            Not default
  ---------------------------------------------------------------------

Keyword index. Formatted on 10/11/98.